How to Connect Arduino Mega 2560 to Raspberry Pi 3 Model B

Hello !

I have a problem to connect my Arduino Mega 2560 to the Raspberry Pi 3 Model B with Serial port,

The Goal of my project is the read Id of NFC Tags, (I use the Itead NFC PN532) and send it from Arduino to Raspberry Pi, and look if the Id is exists or not in the Database MySQL installed in Raspberry pi.

Can you help me please ?